Absolutely Brexit is self harm not often observed in otherwise well developed parts of the world. Is kicking her out a loss for the UK? Probably.
But this lady seems otherwise very capable, and it’s not like they’ve kept it a secret what she needed to do to get settled status, nor is it very difficult… so can’t say I feel too sorry for her.
And Brits living in the EU go through similar processes in those countries, with some “equally unfortunate” getting kicked out.
If you want to live in a country, you really should be responsible to get up to speed on local requirements.